This invention concerns tricyclic benzoheterocyclic carboxyamides which act as vasopressin V2 agonists, as well as methods of treatment and pharmaceutical compositions utilizing these compounds.
Vasopressin (antidiuretic hormone, ADH) a nonapeptide hormone and neurotransmitter, is synthesized in the supraoptic nuclei of the hypothalamus of the brain and transported through the supraoptico-hypophyseal tract to the posterior pituitary where it is stored. Upon sensing an increase in plasma osmolality by brain osmoreceptors or a decrease in blood volume or blood pressure (detected by the baroreceptors and volume receptors), vasopressin is released into the blood circulation and activates vasopressin V1a receptors on blood vessels causing vasoconstriction to raise blood pressure; and vasopressin V2 receptors of the nephron of the kidney causing reabsorption of water and to a lesser degree electrolytes, to expand the blood volume (Cervoni and Chan, Diuretic Agents, in Kirk-Othmer, Encyclopedia of Chemical Technology, 4th ed., Wiley, Volume 8, 398-432, (1993)). The existence of vasopressin in the pituitary was known as early as 1895 (Oliver and Schaefer, J. Physiol. (London), 18, 277-279, (1895)). The determination of the structure and the total synthesis of vasopressin were accomplished by du Vigneaud and coworkers in 1954 (du Vigneaud, Gish and Katsoyannis, J. Am. Chem. Soc., 76, 4751-4752, (1954)).
The actions of vasopressin V1a receptors are mediated through the phosphatidylinositol pathway. Activation of vasopressin V1a receptors causes contraction of the smooth muscle of the blood vessels to raise blood pressure. The actions of the vasopressin V2 receptors are mediated through activation of the adenylate cyclase system and elevation of intracellular levels of cAMP. The activation of vasopressin V2 receptors by vasopressin or vasopressin-like (peptidic or non-peptidic) compounds increases water permeability of the collecting ducts of the nephron and permits the reabsorption of a large quantity of free water. The end result is the formation and excretion of a concentrated urine, with a decrease in urine volume and an increase in urinary osmolality.
Vasopressin plays a vital role in the conservation of water by concentrating the urine at the site of the collecting ducts of the kidney. The collecting ducts of the kidney are relatively impermeable to water without the presence of vasopressin at the receptors and therefore, the hypotonic fluid formed after filtering through the glomeruli, passing the proximal convoluted tubule, the loops of Henle, and the distal convoluted tubules, will be excreted as dilute urine. However, during dehydration, volume depletion or blood loss, vasopressin is released from the brain and activates the vasopressin V2 receptors in the collecting ducts of the kidney rendering the ducts very permeable to water; hence water is reabsorbed and a concentrated urine is excreted. In patients and animals with central or neurogenic diabetes insipidus, the synthesis of vasopressin in the brain is defective and therefore, they produce no or very little vasopressin, but their vasopressin receptors in the kidneys are normal. Because they cannot concentrate the urine, they may produce as much as 10 times the urine volumes of their healthy counterparts and they are very sensitive to the action of vasopressin and vasopressin V2 agonists. Vasopressin and desmopressin, which is a peptide analog of the natural vasopressin, are being used in patients with central diabetes insipidus. Vasopressin V2 agonists are also useful for the treatment of nocturnal enuresis, nocturia, urinary incontinence and temporary delay of urination whenever desirable.
Vasopressin, through activation of its V1a receptors, exerts vasoconstricting effects so as to raise blood pressure. A vasopressin V1a receptor antagonist will counteract this effect. Vasopressin and vasopressin agonists release factor VIII and von Willebrand factor so they are useful for the treatment of bleeding disorders, such as hemophilia. Vasopressin and vasopressin-like agonists also release tissue-type plasminogen activator (t-PA) into the blood circulation so they are useful in dissolving blood clots such as in patients with myocardial infarction and other thromboembolic disorders (Jackson, xe2x80x9cVasopressin and other agents affecting the renal conservation of waterxe2x80x9d, in Goodman and Gilman, The Pharmacological Basis of Therapeutics, 9th ed., Hadman, Limbird, Molinoff, Ruddon and Gilman Eds., McGraw-Hill, New York, pp. 715-731 (1996); Lethagen, Ann. Hematol. 69, 173-180 (1994); Cash et al., Brit. J. Haematol., 27, 363-364 (1974); David, Regulatory Peptides, 45, 311-317 (1993); Burggraaf et al., Cli. Sci., 86, 497-503 (1994)).
The following prior art references describe peptidic vasopressin antagonists: Manning et al., J Med. Chem., 35, 382 (1992); Manning et al., J. Med. Chem., 35, 3895 (1992); Gavras and Lammek, U.S. Pat. No. 5,070,187 (1991); Manning and Sawyer, U.S. Pat. No. 5,055,448 (1991); Ali, U.S. Pat. No. 4,766,108 (1988); Ruffolo et al., Drug News and Perspectives 4(4), 217 (May 1991); Albright and Chan, Curr. Pharm. Des. 3(6), 615 (1997). Williams et al., have reported on potent hexapeptide oxytocin antagonists [J. Med. Chem., 35, 3905 (1992)] which also exhibit weak vasopressin antagonistic activity in binding to V1 and V2 receptors. Peptidic vasopressin antagonists suffer from a lack of oral activity and many of these peptides are non-selective antagonists since they also exhibit partial agonist activity.
Non-peptidic vasopressin antagonists have recently been disclosed. Albright et al. describe tricyclic azepines as vasopressin and oxytocin antagonists in U.S. Pat. No. 5,516,774 (1996); tetrahydrobenzodiazepine derivatives as vasopressin antagonists are disclosed in J. P. 0801460-A (1996); Ogawa et al., disclose benzoheterocyclic derivatives as vasopressin and oxytocin antagonists, and as vasopressin agonists in WO 9534540-A; and Venkatesan et al., disclose tricyclic benzazepine derivatives as vasopressin and oxytocin antagonists in U.S. Pat. No. 5,521,173 (1996).
As mentioned above, desmopressin (1-desamino-8-D-arginine vasopressin) (Huguenin and Boissonnas, Helv. Chim. Acta, 49, 695 (1966)) is a vasopressin agonist. The compound is a synthetic peptide with variable bioavailability. An intranasal route is poorly tolerated and an oral formulation for nocturnal enuresis requires a 10-20 fold greater dose than the intranasal administration.
Albright et al. broadly disclose a subset of tricyclic pyrrolo benzodiazepine indole carboxyamides of the present application, as V1 and/or V2 vasopressin receptor antagonists and oxytocin receptor antagonists in U.S. Pat. No. 5,512,563 (1996); U.S. Pat. No. 5,516,774 (1996); U.S. Pat. No. 5,624,923 (1997); U.S. Pat. No. 5,733,905 (1998); U.S. Pat. No. 5,736,540 (1998); EP 640592 A1 (1995); EP 0 636 625 A2 (1995), inter alia.
Compounds of general structure 16b in Scheme 4 of the above applications, are taught by Albright et al. to possess vasopressin and oxytocin receptors antagonist properties. 
wherein Y=(CH2)n with n=0-2; and R4=H, or lower alkyl (C1-C3).
However, the above indole carboxyamides of general structure 16b, have been found unexpectedly to be vasopressin V2 receptor agonists in vivo, and thus possess different biological profile and clinical utility from those originally disclosed. Thus, rather than having an aquaretic effect, they unexpectedly cause reabsorption of water, i.e. they reduce urine volume and increase urine osmolality.
The compounds of this invention are non-peptidic and have a good oral bioavailability. They are vasopressin V2 receptor agonists, and as such they promote reabsorption of water. They demonstrate no vasopressin V1a receptor agonist effects and, thus, do not raise blood pressure. In contrast, the prior art compounds (except some in WO 9534540-A) are described as vasopressin antagonists at both the V1a and V2 receptors.
This invention relates to novel and known compounds selected from those of formula (I): 
wherein:
X, Y and Z are independently selected from O, S, CH, CH2, N, or NR4;
W is moiety selected from (CH2)n;
n=1-2;
R1, R2 are independently, hydrogen, straight chain alkyl (C1-C6), branched chain alkyl (C3-C7), cycloalkyl (C3-C7), alkoxyalkyl (C2-C7), halogen, straight or branched chain alkoxy (C1-C6), hydroxy, CF3, or perfluoroalkyl (C2-C6);
R3 is hydrogen or a straight chain alkyl group (C1-C6), branched chain alkyl (C3-C7), cycloalkyl (C3-C7), alkoxyalkyl (C2-C7), or hydroxyalkyl (C1-C6);
R4 is selected from hydrogen, or (lower alkyl (C1-C6); and
R5 is selected from halogen or hydrogen;
or a pharmaceutically acceptable salt thereof.
Among the preferred moieties represented by the structure: 
are the following: 
It is understood by those in the art that some of the compounds of this invention depending on the definition of R1, R2, R3, and R4 may contain one or more asymmetric centers and may thus give rise to optical isomers and diastereomers. The present invention includes such optical isomers and diastereomers; as well as the racemic and resolved, enantiomerically pure R and S stereoisomers, which possess the indicated activity. Optical isomers may be obtained in pure form by standard procedures known to those skilled in the art. It is also understood that this invention encompasses all possible regioisomers, and mixtures thereof which possess the indicated activity. Such regioisomers may be obtained in pure form by standard separation procedures known to those skilled in the art.
Also according to the present invention there is provided a method of treating, alleviating or preventing disorders which are remedied or alleviated by vasopressin receptor agonist activity. Methods of this invention for inducing vasopressin agonism in a mammal include, but are not limited to, methods for treating, alleviating or preventing diabetes insipidus, nocturnal enuresis, nocturia, urinary incontinence, bleeding and coagulation disorders, and temporary delay of urination whenever desirable in humans or other mammals, which comprises administering to a human or other mammal an effective amount of a compound or a pharmaceutical composition of the invention.
The present invention accordingly provides a pharmaceutical composition which comprises a compound of this invention in combination or association with a pharmaceutically acceptable carrier. In particular, the present invention provides a pharmaceutical composition which comprises an effective amount of a compound of this invention and a pharmaceutically acceptable carrier or excipient.
The compositions are preferably adapted for oral administration. However, they may be adapted for other modes of administration, for example, parenteral administration for patients suffering from coagulation disorders.
In order to obtain consistency of administration, it is preferred that a composition of the invention is in the form of a unit dose. Suitable unit dose forms include tablets, capsules and powders in sachets or vials. Such unit dose forms may contain from 0.1 to 1000 mg of a compound of the invention and preferably from 2 to 50 mg. Still further preferred unit dosage forms contain 5 to 25 mg of a compound of the present invention. The compounds of the present invention can be administered orally at a dose range of about 0.01 to 100 mg/kg or preferably at a dose range of 0.1 to 10 mg/kg. Such compositions may be administered from 1 to 6 times a day, more usually from 1 to 4 times a day. The compositions of the invention may be formulated with conventional excipients, such as a filler, a disintegrating agent, a binder, a lubricant, a flavoring agent and the like. They are formulated in conventional manner, for example, in a manner similar to that used for known antihypertensive agents, diuretics and xcex2-blocking agents.
Also according to the present invention there are provided processes for producing the compounds of the present invention.
The compounds of the present invention of general formula (I) may conveniently be prepared according to the process shown in Scheme 1. 
Thus, a pyrrolobenzodiazepine of formula (3, wherein W is (CH2)n and n=1-2, R1, R2, and R3 are as defined above) is treated with an appropriately activated heteroaryl carboxylic derivative of formula (2) to provide the desired compounds of formula (I) wherein W, n, R1, R2, R3, R4, R5, X, Y, and Z are as defined above.
The heteroaryl carboxylic acids of general formula (1) may be activated as their acid halides, preferably the chloride (2, J=Cl), and reacted with the pyrrolobenzodiazepine of formula (3) in the presence of an inorganic base such as potassium carbonate in a polar, aprotic solvent such as N,N-dimethylformamide; or an organic base such as 4-dimethylamino pyridine in an aprotic solvent, such as dichloromethane or tetrahydrofuran, at temperatures ranging from xe2x88x9240xc2x0 C. to 50xc2x0 C.
Alternatively, the acylating species of formula (2) can be a mixed anhydride of the corresponding carboxylic acid, such as that prepared by treating said acid with 2,4,6-trichlorobenzoyl chloride in an aprotic organic solvent such as dichloromethane, according to the procedure of Inanaga et al., Bull. Chem. Soc. Jpn., 52, 1989 (1979). Treatment of the mixed anhydride of general formula (2) with the pyrrolobenzodiazepine of formula (3) in an aprotic solvent such as dichloromethane and in the presence of an organic base such as 4-dimethylaminopyridine at temperatures ranging from 0xc2x0 C. to the reflux temperature of the solvent, yields a compound of formula (I) wherein W, n, R1, R2, R3, R4, R5, X, Y, and Z are as defined above.
Alternatively, the activation of the carboxylic acids of general formula (1) can be carried out by reacting said acids with other peptide coupling reagents known to those skilled in the art, in an organic aprotic solvent such as dichloromethane, tetrahydrofuran, N,N-dimethylformamide, or the like, at temperatures ranging from xe2x88x9240xc2x0 C. to 120xc2x0 C.
The activating reagent for the carboxylic acids of formula (1) is ultimately chosen on the basis of its compatibility with the R4 and R5 groups and its reactivity with the tricyclic pyrrolobenzodiazepine of formula (3).
The carboxylic acid intermediates (1) of Scheme 1 are either available commercially, or are known in the art, or can be readily prepared by procedures analogous to those in the literature for the known compounds.
The subject compounds of the present invention were tested for biological activity according to the following procedures.
Vasopressin V2 Agonist Effects of Test Compounds in Normal Conscious Water-Loaded Rats:
Male or female normotensive Sprague-Dawley rats (Charles River Laboratories, Inc., Kingston, N.Y.) of 350-500 g body weight were supplied with standard rodent diet (Purina Rodent Lab. Chow 5001) and water ad libitum. On the day of test, rats were placed individually into metabolic cages equipped with devices to separate the feces from the urine and containers for collection of urine. A test compound or a reference agent was given at an oral dose of 10 mg/Kg in a volume of 10 mL/Kg. The vehicle used was 20% dimethylsulfoxide (DMSO) in 2.5% preboiled corn starch. Thirty minutes after dosing the test compound, rats were gavaged with water at 30 mL/Kg into the stomach using a feeding needle. During the test, rats were not provided with water or food. Urine was collected for four hours after dosing of the test compound. At the end of four hours, urine volume was measured. Urinary osmolality was determined using a Fiske One-Ten Osmometer (Fiske Associates, Norwood, Mass., 02062) or an Advanced CRYOMATIC Osmometer, Model 3C2 (Advanced Instruments, Norwood, Mass.). Determinations of Na+, K+ and Clxe2x88x92 ion were carried out using ion specific electrodes in a Beckman SYNCHRON EL-ISE Electrolyte System analyzer. The urinary osmolality should increase proportionally. In the screening test, two rats were used for each compound. If the difference in the urine volume of the two rats was greater than 50%, a third rat was used. The results of this study are shown in Table 1.